23.1 Overview

Cargo automates and standardizes many aspects of Rust development. Its core functions include:

  • Project Scaffolding: Creating new library or binary projects with a consistent directory structure (cargo new, cargo init).
  • Dependency Management: Automatically downloading and integrating required crates from Crates.io or other sources (e.g., Git repositories) based on declarations in the Cargo.toml manifest file.
  • Building and Running: Compiling code with different optimization levels (debug vs. release), managing incremental builds, and executing binaries (cargo build, cargo run).
  • Testing and Benchmarking: Discovering and executing tests and benchmarks (cargo test, cargo bench). (Covered in Chapter 24).
  • Packaging and Publishing: Preparing crates for distribution and uploading them to Crates.io (cargo package, cargo publish).
  • Tooling Integration: Acting as a frontend for other development tools like the formatter (cargo fmt), linter (cargo clippy), and documentation generator (cargo doc).

Comparison with C/C++ Build Systems and Package Managers

Coming from C or C++, you might be accustomed to using separate tools:

  • Build Systems: Make, CMake, Meson, Ninja, etc., manage the compilation and linking process. Configuration can be complex, especially for cross-platform projects.
  • Package Managers: Conan, vcpkg, Hunter, or system package managers (like apt, yum, brew) handle external library dependencies. Integrating these with the build system often requires manual effort.

Cargo unifies these roles. It manages both the build process (invoking the Rust compiler rustc with appropriate flags) and dependency resolution in a single, integrated tool with a consistent interface across all Rust projects. This significantly simplifies project setup and maintenance compared to the fragmented C/C++ ecosystem.